The time of the second interval of cephalosporin suspension varies, it can be once every 6 hours, once every 8 hours, once every 12 hours, or even once every 24 hours for some drugs. The half-life of cefoperazone, cefuroxime and cefazolin is relatively short, like the half-life of cefazolin is only 1.9 hours, which is less than 2 hours, and the half-life of cefuroxime sodium is only 1.5 hours, therefore, the interval is usually 8 hours once or 12 hours once when the drug is used. For drugs with longer half-life, such as ceftriaxone, the half-life is up to 8 hours, so it can be given once a day, that is, once every 24 hours.